import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import java.sql.*;
import java.io.*;
import javax.imageio.ImageIO;

/**
* Read and Write image into MySQL database as BLOB type
*/
public class TestImageBLOB extends JPanel {
   JPanel pnlRead;
   JPanel pnlWrite;
   JTextField tfIDRead;   // To read image of this ID from database
   JTextField tfIDWrite;  // To write image of this ID to database
   JButton btnRead;       // Read image file
   JButton btnWrite;      // Browse for the image file
   Connection conn = null;    // Database Connection
   BufferedImage img = null;  // Image to be displayed

   /** Constructor: Setup Connection and GUI */
   public TestImageBLOB() {
      // Setup database connection
      try {
         conn = DriverManager.getConnection(
            "jdbc:mysql://localhost:8888/rental_db", "myuser", "xxxx");
      } catch(SQLException ex) {
         ex.printStackTrace();
      }
      
      // Setup GUI
      this.setLayout(new BorderLayout());
      pnlRead = new JPanel();
      this.add(pnlRead, BorderLayout.NORTH);   // Top panel for read image
      pnlWrite = new JPanel();
      this.add(pnlWrite, BorderLayout.SOUTH);  // Bottom panel for write image
      
      pnlRead.add(new JLabel("Read Image for Vehicle No:"));
      tfIDRead = new JTextField("SBA1111A", 10);
      pnlRead.add(tfIDRead);
      btnRead = new JButton("Read Image");
      pnlRead.add(btnRead);
      btnRead.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            // Read image from database for the selected ID
            img = readImage(tfIDRead.getText());
            repaint();
         }
      });
      
      pnlWrite.add(new JLabel("Write Image for Vehicle No:"));
      tfIDWrite = new JTextField("GA5555E", 10);
      pnlWrite.add(tfIDWrite);
      
      btnWrite = new JButton("Select Image");
      btnWrite.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            JFileChooser chooser = new JFileChooser();
            int returnCode = chooser.showOpenDialog(null);
            File file = null;
            if (returnCode == JFileChooser.APPROVE_OPTION) {
               file = chooser.getSelectedFile();  // Path to image
               // Insert image into database for the selected ID
               writeImage(file, tfIDWrite.getText());
               // Show confirmation message (need to check result)
               JOptionPane.showMessageDialog(TestImageBLOB.this,
                     "Image inserted.",  "ImageDemo",
                     JOptionPane.PLAIN_MESSAGE);
            }
         }
      });
      pnlWrite.add(btnWrite);
   }
   
   /** Write the selected image into the database for the given ID */ 
   public void writeImage(File file, String id) {
      try {
         FileInputStream in = new FileInputStream(file);
         PreparedStatement pstmt = conn.prepareStatement(
               "UPDATE vehicles vehicles SET photo=? WHERE veh_reg_no = ?");
         pstmt.setBinaryStream(1, (InputStream)in, (int)file.length());
         pstmt.setString(2, id);
         System.out.println(pstmt);  // for debugging
         int returnCode = pstmt.executeUpdate();
         System.out.println(returnCode + " record updated");
      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
   
   /** Read image from the database for the given ID */
   public BufferedImage readImage(String id) {
      BufferedImage bufImg = null;
      try {
         PreparedStatement pstmt = conn.prepareStatement(
               "SELECT photo FROM vehicles WHERE veh_reg_no = ?");
         pstmt.setString(1, id);
         System.out.println(pstmt);  // for debugging
         ResultSet rset = pstmt.executeQuery();
         // Only one result expected
         rset.next();
         // Read image via InputStream
         InputStream in = rset.getBinaryStream("photo"); 
         // Decode the inputstream as BufferedImage
         bufImg = ImageIO.read(in); 
      } catch(Exception ex) {
         ex.printStackTrace();
      }
      return bufImg;
   }
   
   // Override paintComponent() to perform custom painting
   @Override
   public void paintComponent(Graphics g) {
      super.paintComponent(g);     // paint parent's background
      setBackground(Color.WHITE);  // set background color for this JPanel
      if (img != null) {
         g.drawImage(img, 100, 100, this);
      }
   }
   
   /** Entry main method */
   public static void main(String[] args) {
      // Run the GUI codes on the Event-Dispatching thread for thread safety
      SwingUtilities.invokeLater(new Runnable() {
         @Override
         public void run() {
            JFrame frame = new JFrame("Read/Write Image BLOB Demo");
            TestImageBLOB imgPanel = new TestImageBLOB();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.getContentPane().add(imgPanel);
            frame.setSize(600, 400);
            frame.setVisible(true);
         }
      });
   }
}